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03 February 2013

Fish passage tests

On November 2012, we started new live fish passage tests through an operating VLH.

The new tests were done to a scientific protocol that has been agreed to by the ONEMA Eco Hydraulic Center, to investigate the downstream migration of large migrating fish such as Atlantic salmon and sea trout, both in adult and in youth life stages.

Trout, unlike eels which have been tested in the past by MJ2 and essentially migrate during flooding periods, these  large fish can migrate in more intermediate flood flows.

ONEMA’s goal was to obtain in-situ knowledge of how the VLH relates to such migratory species, considering the VLH operating in an intermediate position, with partially open blades.  The test will investigate the impact of the VLH on two different species, Trout and Carp, with the Trout considered in two sizes to simulate both the adult stage migrating downstream after spawning and young life stage[falling salmon?  Is this not the smolt stage].

Arc en Ciel farmed adult trout between 50 to 70cm length have been selected for the tests, with weights between 1,5 and 3 kg.  In order to simulate young trout a  length of between 18 to 23 cm and a weight between 100 and 200 g was selected.

The tests were organized to start at the beginning of November at the Yenne HPP on the Rhône River, which was kindly hosted by CNR.  Unfortunately, due to bad water conditions caused by significant rainfall and lack of one of the Belley plant group, it was necessary to abandon these tests due to high flows and personal safety concerns.

Tests will start again in mid-April of 2013 in Millau on the new La Glacière plant, which is currently under construction.